When you grow up -- When I grow up? When we grow up? How dare you talk to women that way? Reporter: Anger and desperation on capitol hill during an ugly confrontation between Republican senator orrin hatch and a group of women, a scene playing out over and over. What is wrong with you? Reporter: As protesters launch their final attempt to swing votes against supreme court nominee Brett Kavanaugh. Shame on you! Shame on you! Reporter: It has become one of the most polarizing nominations in our history. Brett and mark came into the bedroom and locked the door behind them. Reporter: Testimony that pitted Christine blasey Ford -- I was pushed onto the bed and Brett got on top of me -- Reporter: Against the man she says sexual assaulted her as a teenager. I've never sexual assaulted anyone, not in high school, not in college, not ever. Reporter: But the protests and the FBI investigations seem to have little impact on the partisan divide. After a critical vote in the senate today -- Ms. Collins? Reporter: It's all but certain Kavanaugh will become the next U.S. Supreme court justice. How do you think Kavanaugh will make us feel? Reporter: Today all eyes on Republican senator Susan Collins from Maine, a key swing vote. I will announce my intentions on how to vote later today. Reporter: Her constituents flooding into her office, trying to be heard. I believe survivors! I believe survivors! Reporter: This week we were with Maine women as they delivered 1,500 letters to Collins' Portland office, sharing deeply personal stories of sexual assault. All these stories are uncomfortable to hear, nobody wants to hear about someone's trauma. Is she listening to our message? I'm not so sure. I hope, though. Reporter: With her friend Marie. The great people from the great state of Maine -- Reporter: As she delivered one last message for her senator, a warning if she votes yes. We are coming for your senate seat. Reporter: By 3:00 today, the friends were watching together in Maine. The senator for Maine? Reporter: As Collins delivered her decision in a 40-minute speech. Thank you, Mr. President. Senator Collins, please vote no! The sergeant in arms will restore order in the gallery -- Senator Collins is trying to walk a fine line. She is a woman, she's been pressured by women. There were women in the gallery shouting "Defend women" as she began her speech. Reporter: Collins lamenting the process that brought her here. Today we have come to the conclusion of a confirmation process that has become so dysfunctional, it looks more like a caricature of a gutter-level political campaign. Reporter: She praised Kavanaugh's legal expertise and said she believes the FBI investigation does not prove that the judge sexual assaulted Dr. Ford. The facts presented do not mean that professor Ford was not sexual assaulted that night, or at some other time. But they do lead me to conclude that the allegations fail to meet the more likely than not standard. Therefore, I do not believe that these charges can fairly prevent judge Kavanaugh from serving on the court. Reporter: Having laid out her thoughts she then announced the decision that all but cemented Kavanaugh as supreme court justice. Mr. President, I will vote to confirm judge Kavanaugh. Shame! Reporter: It was a heartbreaking moment for deannie and Marie. I thought it was a tragic choice that betrayed women, betrayed her constituents -- Reporter: Now they are resolved to make good on their promise to replace Collins. Marie helped start a crowd funding campaign and now that Collins says she'll vote yes, more than $2 million raised by several Maine activist organizations will be held in a trust and eventually donated to fund Collins' opponent in 2020. We will do all we can to take back senator Collins' senate seat and ensure that she never represents us again. Susan Collins was in a no-win situation. If she voted against Kavanaugh, she would have been primaried aggressively on her right. The fact that she is voting for Kavanaugh means Democrats will mount an aggressive campaign to unseat her. Reporter: The FBI investigation into allegations against the nominee, which he denies, includes 46 pages of summaries detailing 10 additional interviews. Not included, interviews with Ford and Kavanaugh themselves. Instead, the FBI apparently relying on their previous sworn testimonies. The FBI never interviewed Dr. Ford. And they never interviewed a number of people who submitted sworn statements that corroborated her allegations. This was not an investigation. This was a sham. Reporter: Arizona senator Jeff flake says without more corroboration, he is also ready to confirm Kavanaugh. I read the report. I'm glad that we did it. You plan to vote yes tomorrow? Unless something big changes. I don't see what would. Reporter: West Virginia's Joe Marcin agreed, another crucial vote. Mr. Manchin -- When Joe Marcin, the only democratic senator to break with his side and side with Republicans, when he announced he was a yes, in front of his office -- Shame, shame, shame! It was flooded with protesters. The senator trying to explain his decision to us reporters -- I believe Dr. Ford -- Then why -- But he was drowned out and ultimately chased out by those who oppose his decision. Republican Lisa murkowski also broke ranks tonight announcing she will not vote for Kavanaugh. I could not conclude that he is the right person for the court at this time. Reporter: A group of native alaskan women who came to rally against Kavanaugh say even though he'll likely be confirmed, their senator did the right thing. Our opinions about who should be sitting on the supreme court count. They count to the senator and that she listens to her constituents. Reporter: One place where today's vote definitely received a positive response, the white house. It's obviously a huge victory for the president. Phe getsanother justice onthe supreme court. But they've also found an issue to energize Republicans. Reporter: While the president may claim a win, political observers say the cost of that victory may be too high for an already divided nation. We have been living with a very poisonous congress for many years now. This incident will make it much, much worse. It's going to be even more dysfunctional than it already has been. ABC news will have full coverage of tomorrow's full senate vote.

This transcript has been automatically generated and may not be 100% accurate.